1. Field of the Invention
The present invention relates to a diluted solution formed by means of alkylene carbonate (hereinafter may be referred to as an alkylene carbonate dilution) which is useful for preparing an aqueous reducing chemical agent (e.g., a No. 1 permanent waving agent); to an alkylene carbonate useful for preparing the alkylene carbonate dilution; and to an aqueous reducing chemical agent.
2. Background Art
Generally, a permanent waving agent includes an aqueous No. 1 agent, which contains a reducing substance, and a No. 2 agent, which contains an oxidizing substance.
One known reducing substance contained in such an aqueous No. 1 agent is a cyclic mercapto compound, which is disclosed in Japanese Patent Application Laid-Open (kokai) No. 2006-265187.
The patent document discloses in paragraph [0009] thereof that the stability of cyclic mercapto compounds in an aqueous solution leaves room for improvement and is to be further enhanced. The patent document also discloses that, since these specific cyclic mercapto compounds gradually decompose over time in an aqueous solution, the cyclic mercapto compound level of a water-containing chemical agent for permanent waving gradually decreases, and undesired coloring, precipitation, etc. which occur in association with decomposition impair the appearance of chemical agent products, thus problematically deteriorating the products.
One approach for solving the problem disclosed in paragraph [0011] of the same patent document is to provide an emulsified hair-treating chemical agent (No. 1 permanent waving agent) containing a cyclic mercapto compound, a surfactant, and water, whereby stability of the cyclic mercapto compound contained in the chemical agent is enhanced.
However, as disclosed in the Examples section of the patent document, percent decomposition of 2-mercapto-4-butyrolactone on test day 10 reaches, in some cases, about 30%. Therefore, such an emulsified chemical agent has a storage stability that still remains to be enhanced, and is not considered a chemical agent sufficiently suitable for mass production and long-term storage.
Under such circumstances, currently, when a No. 1 permanent waving agent containing a cyclic mercapto compound as a reducing substance is employed, the No. 1 permanent waving agent must be reconstituted upon use (just before use of a hair-treating agent).
However, since a cyclic mercapto compound has considerably low solubility in water, reconstitution of the compound upon use is difficult, which is problematic. Specifically, in order to prepare an aqueous solution of a No. 1 permanent waving agent, a cyclic mercapto compound and water must be vigorously stirred together by means of a homomixer (disclosed in paragraph [0093] of the patent document). Thus, reconstitution of the permanent waving agent upon use cannot be employed in practice.